The boiling point of acetone and water is 56⁰C and 100⁰C respectively. Distillation is used to separate miscible liquids which have a boiling point difference of more than 25⁰C.

For fractional distillation, the difference in boiling points should have been less than 25⁰C

Centrifugation and decantation processes are done to separate components of heterogeneous mixtures and not miscible liquids.

So the correct answer is distillation.